demo · v140

Memory Watermark

An OOM crash that lands with no memory context is the worst kind. Snapshot the heap watermark and a count of active long-lived objects (canvases, audio nodes, observers) on every navigation — the moment the tab dies, the report carries the last good reading.

heap used

– MB

DOM nodes

–

active observers

–

awaiting crash

// Run on a 5-second tick or after every route change.
function snapshotMemory() {
  if (performance.measureUserAgentSpecificMemory) {
    performance.measureUserAgentSpecificMemory().then(r => {
      crashReport.set("heap_mb", String(Math.round(r.bytes / 1e6)));
    });
  }
  crashReport.set("dom_nodes", String(document.querySelectorAll("*").length));
  crashReport.set("observers", String(activeObserverCount));
}

why a watermark

You don't ship a memory reading from inside the crash handler — by then the renderer is dead. You ship the last reading. Snapshot on every route change, every visibility change, and every WebGL context creation. When the report lands you can reconstruct: "this user was at 480 MB and 230k DOM nodes when their tab died." Way more actionable than "OOM."

why a watermark

see also